Please identify this plant

That's amazing. Thanks all. Mine has been in a corner and for the last 30 years at least has produced about five stems a year. No spread. I had better not tell it about spreading possibilities.

It's Lysimachia punctata, also known as Yellow Loosestrife, an old cottage garden plant. It spreads quite a bit in damp soil - in my opinion, a bit of a nuisance!

Yes, yellow loosestrife. It's a wild flower, which is perhaps why you couldn't find it if you've been looking at garden flowers. It spreads, but not so much that it's a problem. There is also purple loosestrife, which I think is a different plant altogether, not just a different colour of this one

PlantNet says Loosestrife.